
where \(n_\chi \in \mathbb {Z}, n_\chi \le n,\)  is the degree of the divisor \(\mathcal {D}\) 
such that \(\underline{\alpha }_{Q_0}(\mathcal {D})=\chi .\)  Then by [1]} (Corollary 4.3),
the solution (REF ) is smooth if
and only if \(\textbf {Z}+\textbf {V}x+\textbf {W}t_{\underline{r}}\in i\mathbb {R}^n\) 
and hence \(\textbf {Z}\in i\mathbb {R}^n\) . We complete the proof.
\(\Box \)
